Actuators are used in myriad devices and systems. For example, many vehicles including, for example, aircraft, spacecraft, watercraft, and numerous other terrestrial and non-terrestrial vehicles, include one or more actuators to effect the movement of various control surfaces or components. In many applications, such as, for example, aircraft flight surface control systems and thrust reverser actuation control systems, the actuators that are used may be subject to relatively severe environmental conditions, as well as relatively high magnitude shock and vibration.
As a result of, for example, the environmental conditions, and relatively high magnitude shock and vibration an actuator may experience, the actuator could become jammed or otherwise inoperable, and thereby prevent movement of the actuated component, such as a flight control surface. For example, the actuator gear train could potentially jam or, if the actuator is a ballscrew-type actuator, the ball returns could become jammed. Under such conditions the actuator may “lock up” or otherwise become inoperable, thus obstructing the controlled surface. Though such situations are unlikely, analysis has shown that secondary damage to other portions of the actuator, or to various portions of the system in which the actuator is installed, may result under certain postulated circumstances. For example, if an actuator becomes jammed, it is postulated that all of the drive force supplied from the drive force source could be concentrated on the jammed actuator. This postulated condition may result in damage to the actuator or the system in which it is installed. Repairing such damage can be costly and result in system down time. This postulated condition can also lead to the inability to operate the controlled component, such as a flight control surface. One solution is to use stronger components, but this increases the cost and/or weight of the system. Another solution is to include numerous, independently operated torque limiters or decoupler assemblies. However, this solution may also increase system cost and/or weight.
Accordingly, there is a need for an actuator that improves upon one or more of the drawbacks identified above. Namely, an actuator that reduces the likelihood of component damage if the actuator becomes inoperable by, for example, becoming jammed, without significantly increasing the cost and/or the weight of system components and/or that does not prevent movement of the actuated component by other actuators to which the jammed actuator is connected, thereby reducing the likelihood of, for example, a flight control surface jam event. The present invention addresses one or more of these needs.